Stop light switch



April 24, 1962 H. M. ROBIN-SON 3,031,548

STOP LIGHT SWITCH Filed April 13, 1959 2 Sheets-Sheet 1 /2 4 lg 5INVENTOR.

HER BERT M. RQB] N SON ATTORNEYS STOP LIGHT SWITCH Filed April 13, 19592 Sheets-Sheet 2 li 15 [mil] JNVENTOR. HERBERT M. ROBIN SON T 11ATTORNEYS United States Patent 3. :";31548 STOP LEGHT SWITCH Herhert M.Robinson, 3591 W. (inter Drive, Detroit,

Mich; Fay Robinson, administratrix in estate of Herbert M. Robinson,deceased Filed Apr. 13, 1959, Ser. No. 805,923 4 Claims. (Cl. Nil-81)This invention relates generally to the electrical switch 1 art and,more particularly, to a novel and improved stoplight switch especiallyadapted for use on vehicles such as trucks, tractors, trailers and thelike.

It is the primary object of the present invention to pro- Vlde a novelvehicle stop-light switch which is economical of manufacture, rugged andsimple in construction and efiicient in operation.

It is another object of the present invention to provide a stop-lightswitch which includes a novel and compact piston for moving the contactsof the switch into operative engagement, and which piston is made from aselflubricating and a non-water absorbing material which is functionalwithin the conventional autostandard requirements of temperature,whereby it will operate troublefree in temperatures ranging from 40degrees below zero F. up to 280 F..

It is a further object of this invention to provide a stoplight switchwhich incorporates a contact construction that includes means for makingan electrical contact to complete the circuit to thestop lightssimultaneously at four dilferent points, whereby the usual contact pointheating and arcing which is inherent in a switch of this type is-eliminated. The novel switching and contact structure in this stoplightswitch provides a positive electrical contact and switching action dueto the novelstructure thereof which includes a stationary contact havinga pair of upwardly extended, concave upwardly facing, laterally spacedapart contact arms on each end thereof which are adapted to beelectrically engaged by an equal number of movable, flexible roundedcontacts that are snapped into positive engagement therewith by means ofa coil spring.

It is still another object of the present invention to provide astop-light switch which will possess a long operating life and whereinthe need for repairs is reduced to a minimum and, for all practicalpurposes, is eliminated.

It is a further object of the present invention to provide a stop-lightswitch which may be disassembled for easy and quick maintenance andinspection by merely removing two screws.

Other objects, features and advantages of this invention will beapparent from the following detailed description and appended claims,reference being had to the accompanying drawings forming a part of thespecification wherein like reference numerals designate correspondingparts of the several views.

In the drawings:

FIG. 1 is a side elevational view of a stop-light switch made inaccordance with the principles of the invention;

FIG. 2 is an enlarged top plan view of the structure illustrated in FIG.1;

FIG. 3 is an enlarged bottom plan view of the structure illustrated inFIG. 1;

FIG. 4 is an elevational sectional view of the structure illustrated inFIG. 2, taken along the line 4-4 thereof and looking in the direction ofthe arrows;

FIG. 5 is a fragmentary elevational sectional view similar to FIG. 4 butshowing the contacts engaged to complete a circuit therethrough;

FIG. 6 is a horizontal sectional view of the structure illustrated inFIG. 4, taken along the line 6-6 thereof and looking in the direction ofthe arrows;

FIG. 7 is a horizontal sectional view of the structure ton;

FIG. 13 is an elevational sectional view of the piston illustrated inFIG. 12, taken along the line 13-13 thereof and looking in the directionof the arrows;

FIG. 14 is a top plan view of a spring contact plate employed in theinvention;

FIG. 15 is an elevational sectional view of the structure illustrated inFIG. 14, taken along the line 15-15 thereof and looking in the directionof the arrows;

FIG. 16 is a top plan view of a stationary contact bar employed in theinvention;

FIG. 17 is a front end elevational view of the structure illustrated inFIG. 16;

FIG. 18 is a right side elevational view of the structure illustrated inFIG. 16;

' FIG. 19 is a front elevational view of the operating rod employed inthe invention; and

FIG. 20 is a right side elevational view of the structure illustrated inFIG. 19.

Referring now to the drawings, and in particular to FIGS. 1 through 5,the numeral 10' indicates the body member which is preferably made froma suitable lightweight material as anodized aluminum. The exterior shapeof the body member 10 is preferably hexagonal, whereby, a wrench may beapplied thereto for threading the switch in place. Extending downwardlyfrom the lower end of the body member ill is the tapered threadedextension or fitting member 11 for mounting the switch in the air lineof an air-brake system as normally employed on trucks, busses and thelike. A hole 12 is formed through the fitting member 11 and this holeadmits air under pressure to the switch and communicates with thecylinder 13 which is formed in the upper end of the body member 10. Theupper end of the hole 12 communicates directly with the tapered recess14 which is formed centrally in the lower wall 15 of the body memberll).

As shown in FIGS. 4, 5, l2 and 13, a piston generally indicated by thenumeral 16 is operatively mounted in the cylinder 13. The piston 16 ispreferably made from a polyester type plastic material which isimpervious to moisture and is provided on the lower end thereof with anannular sealing member 17 which is disposed in the annular peripheralgroove 18 for sealing engagement with the cylinder 13. The sealingmember 17 is preferably a conventional silicon 0 ring. The piston 16 isprovided with a second larger annular peripheral groove 19 around theupper end thereof which communicates with the four evenly disposed slots2%} which are formed in the upper end face of the piston. The piston 16is also functional within the conventional auto standard requirements oftemperature, that is, it will operate trouble-free in temperaturesranging from 40 degrees below Zero F. up to approximately 280 F. Thegood operating characteristics of the piston 16 is due in part to theplastic material from which it is made and in part to the constructionof the piston including the annular groove 19 and the slots 20 whichprevents swelling and consequent jamming of the piston in the cylinder.

As shown in FIGS. 4, l9 and 20, the lower end of the FIG. 12 is a topplan view of the stop-light switch pisv the upper end of the cylinder.13.

' operatingrod 21 is seated in the hole 22 formed in the side thereofwhich is seated in the upper end of the cylinder 13. The spacer plate 24also functions toenclose As best seen in PEG. 1 9, the upper end of theoperating rod 21 is recessed as at 26, and, extending upwardly into thisrecess is the spring retainer finger 27. A spring 28 is seated in therecess 26 with the lower end thereof disposed around the retainer finger27. The upper end of the spring 28 is seated in the hole 29 which iscentrally formed in the boss 30 on the switch cap generally desig natedby the numeral 31. As best seen in FlGS. 8'and 9,

the upper end of the operating rod extends intothe hole 29 and the twodiametrical recesses 32 which communicats with the hole 29'. It will beseen that the spring 23 i normally functions to bias or urge theoperating rod 21 downwardly which in turn forces the piston 16 to theinoperativeposition shown in FIG. 4. The switch cap 31 'is releasablysecured to the body member It by means of the two screws 33 which extenddownwardly through the holes 34 in the capand the holes 35 in the spacerplate 24 and into a threadable engagement with the body member a Asshown in FIGS.'?., 7, l6 and 17, the stop-light switch includes a pairof contact bars generally indicated by the numerals 36 and 36a. Thesecontact bars aresubstantially Y-shaped and are identical andinterchangeable, and the various parts thereof have been marked withcorresponding reference numerals followed by the small letter isconnectedto a conductor as 37 at the outer'end thereof by means of thescrew 38. The contact bars 36 and 36a are preferably made from silverplated #18 gage sheet brass. The contact bar 36 includes the connectorplate enemas.

has the ends thereof connected to the pair of contact members 54 in theslots 57. The inner end of each of the contact members 54 is slotted asat 58 for the reception of the spring 56. The inner ends 59 of eachcontact member 54 are adapted to be rockably mounted in the grooves 69formed on each side of the operating bar21 on each side of the hole 55.As shown in FIGS. 4 and 15, the outer ends of each contact member 54 arearcuately formed into a circular construction so that they will make apair of firm contacts with the stationary contact members 42 and 43 onthe contact members 39 and 39a.

.The reverse curve upper ends 46 and 47 on-the stationary contactspermits smooth engagement between the contact members 54 and 39 withouthindrance or binding in any manner. Y

In operation, the air under pressure would be admitted into the cylinder13 by meansof the passage 12 when the operator Works the usual brakepedal (not shown). The air under pressure will move the piston 16upwardly which in turn moves the operating'rod 21 upwardly againstthepressure of the return spring 28. The curved contact being handled byonly one contact or point area. The.

novel contact sturucture of this switch materially reduces the usualpoint heating and arcing which is inherent in a switch of this type. Thecap 31 is made from a suitable plastic insulating material, a i I Thenovelswitching andcontact structure in this stoplight switch provides apositive electrical contact and Iii switching action due to thefact thatit employs a stationary A contact havinga pair of upwardly extended,concave up- Wardlyfacing, laterally spaced apart contact arms on each Asshown in FIGS. 16 and 17, the contact bar 36 i are reversely curvedoutwardly as indicated by the numerals 46 and 47, respectively. Theportion 39 of the contact bar is disposed in the entrance slot 43 formedin the wall of the switch cap 31. The other contact bar portion 39a isdisposed in a similar slot 48a at a diametrically opposite position. Theswitch cap 31 is provided with the circular recess 49 in the lower endthereof. which communicates with the recess 29 andwhich is provided withthe two oppositely disposed slots 50. As shown in FIG. 7, the contactbar portions 40 and 41 are adapted to lie in the recess 49, and thecontact portions 42 and 43 are adapted to lie in the slots 50. As shownin FIG. 7 the switch cap 31 is provided with the rounded locatingprojection 51 which extends into the slot 48 and into a mating curvedrecess 52 formed in the side of the contact 7 bar portion 39. As shownin FIGS. 10 and 11, the spacer plate 24 is'provided with the circularlyspaced apart loeating projections 53 on the upper face thereof forlocating the contact bar portions 39.

ating rod 21 is provided with a hole 55 through the center portionthereof, adjacent the upper end. Operatively mounted through the hole 55is the coil spring 56 which end thereof, which are adapted to beelectrically engaged by an equal number of movable, flexible roundedcontacts of the switch insures a positive contact every time the switch.is operated regardless of any tilting of the'rhovable contacts relativeto the stationary contacts. In'the prior stop-light switches there is apoint in the contacti making movement of the contact structure whereinarcing will occur and this inherent defect of *the prior switches is notpresent in the instant switch, because"the switching action thereof isinstantaneous without any delay or lagging action, whereby, the contactsare adapted to instantaneously either make or break contact with eachother. e i

While it will be apparent that;the preferred embodiments of theinvention herein disclosed are well calculated to fulfill the objectsabove stated, it will be appreciated that the invention is susceptibletomodification, variation and change without departing from the properscope or fair meaning of the subjoined claims. It will be seen that whenthe circular, flexible contact members 54 are in the contact making oroperative. position, as shown in FIGS, theyare seated secu'rely'in themating concave contact arms 44 and 45 to provide a large; continuous andfirm contact surface area therebetween.

The contact members 54 are preferably made from berylpressure isreleased from'the piston 16, thereturn spring Q 28 will move theoperating rod 21 downwardly and the circular contacts 54 will be forcedoutwardly sidewardly by means of their inner ends pivoting in therecesses 60 on the operating rod 21. It will thus be seen that thedownward pressure of spring 56 on the contacts 54 will be decreased tothe zero point during such release action. However, because of theflexible curved ends of the contacts 54, a firm contact will bemaintained until the operating rod 21 is below the neutral point in itsmovement. Up to the time that the neutral point is reached, and thecontacts are disengaged, the curved contacts 54 will flex and maintaincflicient contact with the stationary contact arms 44 and 45 and willride all of these arms with a smooth snapping action, when the operatingrod moves beyond the neutral position, because of the reverse curvedends 46 and 47 of the arms 44 and 45, respectively. The springs 28 and56 are preferably made from stainless steel spring wire. It will beunderstood, that the silicon O ring 17 possesses good inherentself-lubricating characteristics. It will be seen that the contact bars36 and 36a are fixedly secured to the spacer plate 24 by means of therivets 61.

What I claim is:

1. A stop light switch, comprising: a body member 1 provided with afitting for mounting the switch in a vehicle fluid pressure brakesystem; a piston mounted in said body member and being movable by fluidunder pressure; a spacer plate mounted on said body member; a pair ofoppositely disposed spaced apart stationary contact members mounted onsaid spacer plate; a cap mounted on said spacer plate; a piston rodconnected to said piston and extended upwardly through said spacer plateand into said cap; means in said cap for normally biasing said pistonrod downwardly; each of said stationary contact members having aplurality of upwardly facing concave contact areas; a movable contactmeans carried on said piston rod; said movable contact means having aplurality of flexible rounded contact ends movable into engagement withsaid concave contact areas on the stationary contact members toelectrically connect the same when said piston is moved upwardly byfluid under pressure and disengageable by said biasing means when thefluid pressure on the piston is released.

2. A stop light switch, comprising: a body member provided with afitting for mounting the switch in a vehicle fluid pressure brakesystem; a piston mounted in said body member and being movable by fluidunder pressure; a spacer plate mounted on said body member; a pair ofoppositely disposed spaced apart stationary contact members mounted onsaid spacer plate; a cap mounted on said spacer plate; a piston rodconnected to said piston and extended upwardly through said spacer plateand into said cap; means in said cap for normally biasing said pistonrod downwardly; each of said stationary contact members having aplurality of upwardly facing concave contact areas; a movable contactmeans carried on said piston rod; said movable contact means including apair of contact plates having their inner ends pivotally mounted onopposite sides of the piston rod; a pair of flexible rounded contactmembers formed on the outer end of each of said contact plates; and, aspring interconnected between said contact plates and operable to biassaid contact plates upwardly into an inoperative position when saidbiasing means has moved the piston rod downwardly, and to bias thecontact plates downwardly when the piston rod is moved upwardly by saidpiston to move the rounded contact members into engagement with saidconcave contact areas on the stationary contact members to electricallyconnect the same.

3. In a stop light switch of the class described, the combination,comprising: a body member having a cylinder formed therein; a pistonmovably mounted in said cylinder and movable upwardly by fluid underpressure; a contact housing carried on said body member; a piston rodextended upwardly from said piston and into said contact housing; meansin said housing for normally biasing said piston rod downwardly; a pairof oppositely disposed spaced apart stationary contact members in saidhousing; each of said stationary contact members having a pair of endportions which curve upwardly to form a contact pocket and then curveoutwardly to provide a reversely curved contact guide means; a movablecontact means carried on said piston rod; said movable contact meansincluding a pair of contact plates having their inner ends pivotallymounted on opposite sides of the piston rod; a pair of flexible roundedcontact members formed on the outer end of each of said contact plates;and, a spring interconnected between said contact plates and operable tobias said contact plates upwardly into an inoperative position when saidbiasing means has moved the piston rod downwardly, and to bias thecontact plates downwardly when the piston rod is moved upwardly by saidpiston to move the rounded contact members into engagement with saidcontact pockets on the stationary contact members to electricallyconnect the same.

4. In a switch, the combination, comprising: a body member; a contacthousing carried on said body member; a pair of oppositely disposedspaced apart stationary contact members in said housing; each of saidstationary contact members having a pair of end portions which curveoutwardly to form a contact pocket and then curve sidewardly outwardlyto provide a reversely curved contact guide means; an operating roddisposed in said contact housing; a movable contact means carried onsaid rod and including a pair of contact plates having their inner endspivotally mounted on opposite sides of the operating rod; at least apair of flexible rounded contact members formed on the outer end of eachof said contact plates; actuating means for moving said rod; a springinterconnected between said contact plates and operable to bias saidcontact plates into a first position spaced from said contact memberswhen the operating rod is moved in one direction, and to bias thecontact plates into a second position when the operating rod is moved inthe opposite direction to move the rounded contact members to a secondposition into engagement with said contact pockets on the stationarycontact members to electrically connect the same.

References Cited in the file of this patent UNITED STATES PATENTS1,909,699 Mahan May 16, 1933 1,919,817 Wilcox July 25, 1933 2,172,412Robinson Sept. 12, 1939 2,188,948 Huebner Feb. 6, 1940 2,629,791 LeTourneau Feb. 24, 1953 2,752,447 Shatter June 26, 1956 2,791,658 BeemanMay 7, 1957

